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Appendicitis (inflammation of the appendix) is potentially

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Re: Appendicitis (inflammation of the appendix) is potentially [#permalink]

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New post 22 Apr 2015, 11:57
Hi,
Can someone please explain what below sentence means?
"Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before".
especially the "without performing any fewer necessary ones" is difficult to understand.
Does this mean that "doctors can avoid unnecessary removals without performing unnecessary removal operations?"
combination of without+however+fewer is confusing to me.

Thanks in advance

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Re: Appendicitis (inflammation of the appendix) is potentially fatal [#permalink]

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New post 17 Jun 2015, 16:26
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Re: Appendicitis (inflammation of the appendix) is potentially [#permalink]

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andy2andy wrote:
Hi,
Can someone please explain what below sentence means?
"Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before".
especially the "without performing any fewer necessary ones" is difficult to understand.
Does this mean that "doctors can avoid unnecessary removals without performing unnecessary removal operations?"
combination of without+however+fewer is confusing to me.

Thanks in advance


What it means is that with help of new machine, doctors will perform the necessary surgeries no less than the count they were performing earlier. This is only possible when misdiagnoses are only for the ones who do not have appendicitis.

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Re: Appendicitis (inflammation of the appendix) is potentially fatal [#permalink]

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New post 16 Aug 2015, 09:05
Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with symptoms strongly suggesting appendicitis almost have their appendix removed. The appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases. A newly developed internal scan for appendicitis is highly accurate, producing two misdiagnoses for every 98 correct diagnoses. Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before, since .......

Which of the following logically completes the passage?

A. the patients who are correctly diagnosed with this test as not having appendicitis invariably have medical conditions that are much less serious than appendicitis
B. the misdiagnoses produced by this test are always instances of attributing appendicitis to someone who does not, in fact, have it
C. all of the patients who are diagnosed with this test as having appendicitis do, in fact,have appendicitis
D. every patient who is diagnosed with this test as having appendicitis has more than one of the symptoms generally associated with appendicitis
E. the only patients who are misdiagnosed using this test are patients who lack one or more of the symptoms that are generally associated with appendicitis

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Re: Appendicitis (inflammation of the appendix) is potentially fatal [#permalink]

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krutik123 wrote:
Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with symptoms strongly suggesting appendicitis almost have their appendix removed. The appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases. A newly developed internal scan for appendicitis is highly accurate, producing two misdiagnoses for every 98 correct diagnoses. Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before, since .......

Which of the following logically completes the passage?

A. the patients who are correctly diagnosed with this test as not having appendicitis invariably have medical conditions that are much less serious than appendicitis
B. the misdiagnoses produced by this test are always instances of attributing appendicitis to someone who does not, in fact, have it
C. all of the patients who are diagnosed with this test as having appendicitis do, in fact,have appendicitis
D. every patient who is diagnosed with this test as having appendicitis has more than one of the symptoms generally associated with appendicitis
E. the only patients who are misdiagnosed using this test are patients who lack one or more of the symptoms that are generally associated with appendicitis



We need to find a reason to support the conclusion by the author that by using this test, the doctors cab avoid UNNECESSARY SURGERIES and keep performing the NECESSARY SURGERIES.
The argument tells us that the test misdiagnoses 2 cases for every 98 correct ones.
What if the two MISDIAGNOSED cases are NECESSARY SURGERIES?If yes, then the conclusion will break.
So cover the weakness and hence strengthen the conclusion we need to put up some kind of evidence that the NECESSARY SURGERIES will not be MISDIAGNOSED by the test.

C does answer that potential weakness and hence is strengthener.
C says that the two misdiagnosed cases were NOT Neccesary surgeries.

Hope the above helps!!

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Appendicitis (inflammation of the appendix) is potentially fatal.... [#permalink]

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Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with symptoms strongly suggesting appendicitis almost have their appendix removed. The appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases. A newly developed internal scan for appendicitis is highly accurate, producing two misdiagnoses for every 98 correct diagnoses. Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before, since .......

Which of the following logically completes the passage?

A. the patients who are correctly diagnosed with this test as not having appendicitis invariably have medical conditions that are much less serious than appendicitis
B. the misdiagnoses produced by this test are always instances of attributing appendicitis to someone who does not, in fact, have it
C. all of the patients who are diagnosed with this test as having appendicitis do, in fact,have appendicitis
D. every patient who is diagnosed with this test as having appendicitis has more than one of the symptoms generally associated with appendicitis
E. the only patients who are misdiagnosed using this test are patients who lack one or more of the symptoms that are generally associated with appendicitis

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Re: Appendicitis (inflammation of the appendix) is potentially fatal.... [#permalink]

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1) Appendicitis is potentially fatal
2) 20% surgeries are unnecessary
3) New scan detects 98% cases correctly
4) => It leaves out 2% cases
5) Argument says that it is still OK to use and will still ensure that doctors won't skip surgery where it is needed.

This has to be based on the fact that 2% are always false positives (don't have appendicitis, but are detected as having it) rather than false negatives (have appendicitis, but not detected). This is because, if 2% are false negatives, these will potentially cause deaths. However if these are false positives, maybe 2% patients will have it removed when they didn't need to, but this is still better than 20% unnecessary surgeries, and as the surgery is safe, there is no hazard to these 2%.

So, (B) is correct.

Prajat wrote:
Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with symptoms strongly suggesting appendicitis almost have their appendix removed. The appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases. A newly developed internal scan for appendicitis is highly accurate, producing two misdiagnoses for every 98 correct diagnoses. Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before, since .......

Which of the following logically completes the passage?

A. the patients who are correctly diagnosed with this test as not having appendicitis invariably have medical conditions that are much less serious than appendicitis
B. the misdiagnoses produced by this test are always instances of attributing appendicitis to someone who does not, in fact, have it
C. all of the patients who are diagnosed with this test as having appendicitis do, in fact,have appendicitis
D. every patient who is diagnosed with this test as having appendicitis has more than one of the symptoms generally associated with appendicitis
E. the only patients who are misdiagnosed using this test are patients who lack one or more of the symptoms that are generally associated with appendicitis

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Re: Appendicitis (inflammation of the appendix) is potentially [#permalink]

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Imagine there were 100 patients earlier out of whom 80 had appendicitis and 20 didn’t. But all 100 were given surgery (although only 80 were necessary and 20 were not necessary).

With the test that is 98% accurate, there are 2 extreme possibilities:

Case 1:

80 people have appendicitis; the test says all 80 have it.
20 people don’t have appendicitis; the test says 18 don’t have it and 2 have it. In this case 18 out of 20 unnecessary will be avoided and the doctors will still perform 82 surgeries (more than the necessary number 80). So this satisfies all the conditions. This case will be obtained when someone who doesn’t have appendicitis is diagnosed to have it. Option B says the same.

Case 2:

20 people don’t have appendicitis; the test says all 20 don’t have it.
80 people have appendicitis; the test says 78 have it and 2 don’t have it. In this case 2 necessary ones will also be avoided. The doctors will perform 78 surgeries (fewer than the necessary number 80). So this doesn’t satisfy any condition.

In a test, a false positive refers to a diagnosis that mistakenly indicates that a condition, disease or infection is present. A false negative refers to a diagnosis that mistakenly indicates that a disease, infection or condition is absent. A false positive result from a doping test could ruin the career of an honest cyclist. A false negative result on a paternity test could prevent a father and son from reuniting.

Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix (eliminate false positives) without, however, performing any fewer necessary ones than before (i.e. without producing more false negatives), since .....

It seems clear that before this test was developed, doctors removed the appendix of everybody who either had appendicitis or seemed to have it (false positives).

This test has an accuracy rate of 98%, but in order for the conclusion to be true, these few mistakes must involve cases in which people without appendicitis are deemed to have it (false positives) , not the other way around. In other words, these mistakes cannot involve genuine cases of appendicitis that are classified as having nothing to do with appendicitis (false negatives), or else doctors would be performing newer necessary operations (i.e. operations on appendicitis patients) than before.

The part in bold basically means that, with the test, they'll still perform the same number of necessary operations (as they used to). In other words, they'll catch people who have appendicitis just as much as they used to.

To complete this argument we need to find some evidence that supports the conclusion (notice the keyword "since").

How can we support the conclusion that they'll catch just as many people who have appendicitis as they used to?
Well, if the 2% error rate is exclusively due to the test saying you have appendicitis when you don't (rather than not catching your appendicitis), then the author's argument is supported (since the error rate without the test is 20%)...that's essentially what choice B says.

If the 2% error rate were due to the test not catching your appendicitis, then the author's conclusion that the test would decrease the number of unnecessary operations is clearly weakened: the test would be decreasing the number of NECESSARY operations--clearly a bad outcome. Because the denial of choice B hurts the argument, choice B must be evidence that supports the argument.

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Re: Appendicitis (inflammation of the appendix) is potentially fatal [#permalink]

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Surprised to see the comment with most kudos is advocating the wrong answer C.

Argument says:

Before you had a test whereby out of 100 people, say 50 had appendicitis and 50 did not. It correctly identified 50 cases of necessary appendicitis but also mis-diagnosed 20 of them.

Now because the condition is so potentially dangerous, you can live with the extra 20 that got operated un-necessarily.

OA is B because it states

"new procedure gives 98% accuracy so it's better". Going back to our numbers, that's saying we capture the 50 who had appendicitis and now our error is only 2 people. Of those 2 people they don't actually have appendicitis and operating them won't kill them.

So the doctors are happier.

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Re: Appendicitis (inflammation of the appendix) is potentially fatal [#permalink]

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New post 31 Jul 2016, 22:56
GMBA85 wrote:
Which of the following most logically completes the passage?

Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with symptoms strongly suggesting appendicitis almost have their appendix removed. The appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases. A newly developed internal scan for appendicitis is highly accurate, producing two misdiagnoses for every 98 correct diagnoses. Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before, since .

A. the patients who are correctly diagnosed with this test as not having appendicitis invariably have medical conditions that are much less serious than appendicitis

B. the misdiagnoses produced by this test are always instances of attributing appendicitis to someone who does not, in fact, have it

C. all of the patients who are diagnosed with this test as having appendicitis do, in fact, have appendicitis

D. every patient who is diagnosed with this test as having appendicitis has more than one of the symptoms generally associated with appendicitis

E. the only patients who are misdiagnosed using this test are patients who lack one or more of the symptoms that are generally associated with appendicitis

Can someone also explain what does the last line mean?


can someone explain why 'B' is correct.
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Re: Appendicitis (inflammation of the appendix) is potentially [#permalink]

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New post 04 Aug 2016, 03:26
Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Re: Appendicitis (inflammation of the appendix) is potentially [#permalink]

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New post 15 Sep 2016, 08:19
Hi
Can someone explain the difference b/w B and E plz :(
They look almost the same to me..
Been able to eliminate A/C/D
Regards,
Abhishek

nilesh376 wrote:
Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with symptoms strongly suggesting appendicitis almost have their appendix removed. The appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases. A newly developed internal scan for appendicitis is highly accurate, producing two misdiagnoses for every 98 correct diagnoses. Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before, since ____________

A. the patients who are correctly diagnosed with this test as not having appendicitis invariably have medical conditions that are much less serious than appendicitis
B. the misdiagnoses produced by this test are always instances of attributing appendicitis to someone who does not, in fact, have it
C. all of the patients who are diagnosed with this test as having appendicitis do, in fact,have appendicitis
D. every patient who is diagnosed with this test as having appendicitis has more than one of the symptoms generally associated with appendicitis
E. the only patients who are misdiagnosed using this test are patients who lack one or more of the symptoms that are generally associated with appendicitis

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CR from prep <Appendicitis (inflammation of the appendix) > [#permalink]

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New post 17 Sep 2016, 07:33
Hi,
I know this CR question from prep has been discussed.

"Which of the following most logically completes the passage?

Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with symptoms strongly suggesting appendicitis almost always have their appendix removed. The appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases. A newly developed internal scan for appendicitis is highly accurate, producing two misdiagnoses for every 98 correct diagnoses. Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before, since ____________. "

"A. the patients who are correctly diagnosed with this test as not having appendicitis invariably have medical conditions that are much less serious than appendicitis

B. the misdiagnoses produced by this test are always instances of attributing appendicitis to someone who does not, in fact, have it

C. all of the patients who are diagnosed with this test as having appendicitis do, in fact, have appendicitis

D. every patient who is diagnosed with this test as having appendicitis has more than one of the symptoms
generally associated with appendicitis

E. the only patients who are misdiagnosed using this test are patients who lack one or more of the symptoms that
are generally associated with appendicitis "


However, I am quite confused b/w B and E.
Kindly note that I new to this forum,So pretty unsure about the posting rules.

Reagrds,
Abhishek Sinha

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Appendicitis (inflammation of the appendix) is potentially [#permalink]

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abhishek03050 wrote:
Hi,
I know this CR question from prep has been discussed.

"Which of the following most logically completes the passage?

Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with symptoms strongly suggesting appendicitis almost always have their appendix removed. The appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases. A newly developed internal scan for appendicitis is highly accurate, producing two misdiagnoses for every 98 correct diagnoses. Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before, since ____________. "

"A. the patients who are correctly diagnosed with this test as not having appendicitis invariably have medical conditions that are much less serious than appendicitis

B. the misdiagnoses produced by this test are always instances of attributing appendicitis to someone who does not, in fact, have it

C. all of the patients who are diagnosed with this test as having appendicitis do, in fact, have appendicitis

D. every patient who is diagnosed with this test as having appendicitis has more than one of the symptoms
generally associated with appendicitis

E. the only patients who are misdiagnosed using this test are patients who lack one or more of the symptoms that
are generally associated with appendicitis "


However, I am quite confused b/w B and E.
Kindly note that I new to this forum,So pretty unsure about the posting rules.

Reagrds,
Abhishek Sinha


There is no need to open a new topic - just add your comment in the previous thread. For this one, I have merged your new topic with the previous one.

Coming to your query:

Misdiagnosis can be of two types:
False positive: A person who does not have appendicitis is identified as having appendicitis.... this leads to unnecessary operation.
False negative: A person who has appendicitis is identified as not having appendicitis.... this leads to faulty release of the patient without operation.

Option B implies that the misdiagnoses are always "false positive" type. There is no chance of getting a "false negative", i.e. there are 2% false positive misdiagnoses and 0% false negative misdiagnosis.

The latter implies that there is no way that that a person who has appendicitis is identified as not having appendicitis. Hence necessary operations are not going to be reduced, since the test does not produce a single case of "false negative".

On the other hand because the test is 98% accurate (only 2% "false positive" misdiagnosis), there will be drastic reduction of unnecessary operations (though they cannot be eliminated altogether).

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Re: Appendicitis (inflammation of the appendix) is potentially [#permalink]

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New post 17 Sep 2016, 09:03
Hi Sayantan,

Sincere apologies for the inconvenience and the trouble caused.

Went through your explanation. Took me some time to digest it.However, I believe now I have got the
difference. Your Detailing of "False Positive /Negative" helped.

Thanks Again :-D

sayantanc2k wrote:
abhishek03050 wrote:
Hi,
I know this CR question from prep has been discussed.

"Which of the following most logically completes the passage?

Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with symptoms strongly suggesting appendicitis almost always have their appendix removed. The appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases. A newly developed internal scan for appendicitis is highly accurate, producing two misdiagnoses for every 98 correct diagnoses. Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before, since ____________. "

"A. the patients who are correctly diagnosed with this test as not having appendicitis invariably have medical conditions that are much less serious than appendicitis

B. the misdiagnoses produced by this test are always instances of attributing appendicitis to someone who does not, in fact, have it

C. all of the patients who are diagnosed with this test as having appendicitis do, in fact, have appendicitis

D. every patient who is diagnosed with this test as having appendicitis has more than one of the symptoms
generally associated with appendicitis

E. the only patients who are misdiagnosed using this test are patients who lack one or more of the symptoms that
are generally associated with appendicitis "


However, I am quite confused b/w B and E.
Kindly note that I new to this forum,So pretty unsure about the posting rules.

Reagrds,
Abhishek Sinha


There is no need to open a new topic - just add your comment in the previous thread. For this one, I have merged your new topic with the previous one.

Coming to your query:

Misdiagnosis can be of two types:
False positive: A person who does not have appendicitis is identified as having appendicitis.... this leads to unnecessary operation.
False negative: A person who has appendicitis is identified as not having appendicitis.... this leads to faulty release of the patient without operation.

Option B implies that the misdiagnoses are always "false positive" type. There is no chance of getting a "false negative", i.e. there are 2% false positive misdiagnoses and 0% false negative misdiagnosis.

The latter implies that there is no way that that a person who has appendicitis is identified as not having appendicitis. Hence necessary operations are not going to be reduced, since the test does not produce a single case of "false negative".

On the other hand because the test is 98% accurate (only 2% "false positive" misdiagnosis), there will be drastic reduction of unnecessary operations (though they cannot be eliminated altogether).

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Re: Appendicitis (inflammation of the appendix) is potentially [#permalink]

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Please explain this if you were to explain it to a 10 year old :/

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Re: Appendicitis (inflammation of the appendix) is potentially [#permalink]

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New post 31 Jul 2017, 11:52
Merged topics. Please, search before posting questions!
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Appendicitis (inflammation of the appendix) is potentially [#permalink]

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New post 02 Aug 2017, 05:49
sayantanc2k wrote:
abhishek03050 wrote:
Hi,
I know this CR question from prep has been discussed.

"Which of the following most logically completes the passage?

Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with symptoms strongly suggesting appendicitis almost always have their appendix removed. The appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases. A newly developed internal scan for appendicitis is highly accurate, producing two misdiagnoses for every 98 correct diagnoses. Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before, since ____________. "

"A. the patients who are correctly diagnosed with this test as not having appendicitis invariably have medical conditions that are much less serious than appendicitis

B. the misdiagnoses produced by this test are always instances of attributing appendicitis to someone who does not, in fact, have it

C. all of the patients who are diagnosed with this test as having appendicitis do, in fact, have appendicitis

D. every patient who is diagnosed with this test as having appendicitis has more than one of the symptoms
generally associated with appendicitis

E. the only patients who are misdiagnosed using this test are patients who lack one or more of the symptoms that
are generally associated with appendicitis "


However, I am quite confused b/w B and E.
Kindly note that I new to this forum,So pretty unsure about the posting rules.

Reagrds,
Abhishek Sinha


There is no need to open a new topic - just add your comment in the previous thread. For this one, I have merged your new topic with the previous one.

Coming to your query:

Misdiagnosis can be of two types:
False positive: A person who does not have appendicitis is identified as having appendicitis.... this leads to unnecessary operation.
False negative: A person who has appendicitis is identified as not having appendicitis.... this leads to faulty release of the patient without operation.

Option B implies that the misdiagnoses are always "false positive" type. There is no chance of getting a "false negative", i.e. there are 2% false positive misdiagnoses and 0% false negative misdiagnosis.

The latter implies that there is no way that that a person who has appendicitis is identified as not having appendicitis. Hence necessary operations are not going to be reduced, since the test does not produce a single case of "false negative".

On the other hand because the test is 98% accurate (only 2% "false positive" misdiagnosis), there will be drastic reduction of unnecessary operations (though they cannot be eliminated altogether).


For me, this is a very hard question. Sayantan, any tips in general to improve ones analytical bend as much as possible? I dont think that any prep course technique would be able to help much in such questions; it would be come down to one's analytical skills.

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This question is a bit ridiculous and hinges on people's knowledge of false-positives and false-negatives, which I don't think is very fair.

Let's explain B in extreme simple terms so that people can understand - probably grammatically odd but I'm going to try to convey the message in extreme simple terms.


Necessary Surgeries: Perform surgery on ALL PEOPLE that actually HAVE ISSUE.
Unnecessary Surgeries: Perform surgery on ANYONE that DO NOT HAVE ISSUE.

False-positive: People who DO NOT HAVE ISSUE shown as HAVE. This increases unnecessary surgeries.
False-negative: People who HAVE ISSUE shown as NOT. This decreases necessary surgeries.


Statement: TEST DECREASES Unnecessary Surgeries (given in previous statements); yet TEST does NOT DECREASE Necessary Surgeries because ________.

From statements above, clearly if there are NO False-Negatives then there will be NO DECREASE in Necessary surgeries.

(B) All misdiagnosis are FALSE-POSITIVES. In other words, there are NO False-Negatives.
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